package com.hmdp.utils;

import cn.hutool.core.lang.UUID;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;

import java.util.Collections;
import java.util.concurrent.TimeUnit;

public class SimpleRedisLock implements  ILock {

    private StringRedisTemplate stringRedisTemplate;
    private String lockName;

    public SimpleRedisLock(StringRedisTemplate stringRedisTemplate, String lockName) {
        this.stringRedisTemplate = stringRedisTemplate;
        this.lockName = lockName;
    }



    private static final String KEY_PREFIX="lock:";
    private static final String ID_PREFIX = UUID.randomUUID().toString(true) + "-";

    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    static {
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }
    @Override
    public boolean tryLock(long timeoutSec) {
        String threadId = ID_PREFIX + Thread.currentThread().getId();
        Boolean success = stringRedisTemplate.opsForValue().setIfAbsent(KEY_PREFIX + lockName, threadId, timeoutSec, TimeUnit.SECONDS);
        return Boolean.TRUE.equals(success);
    }

    /**
     * 使用lua脚本释放锁，不存在原子性问题
     */
    @Override
    public void unlock() {
        // 调用lua脚本
        stringRedisTemplate.execute(
                UNLOCK_SCRIPT,
                Collections.singletonList(KEY_PREFIX + lockName),
                ID_PREFIX + Thread.currentThread().getId());
    }

    /**
     * 存在原子性问题的释放锁
     */
//    @Override
//    public void unlock() {
//        String redisValue = stringRedisTemplate.opsForValue().get(KEY_PREFIX + lockName);
//
//        // 获取线程标示
//        String threadId = ID_PREFIX + Thread.currentThread().getId();
//
//        if( !redisValue.equals(threadId)) {
//            return;
//        }
//
//        stringRedisTemplate.delete(KEY_PREFIX + lockName);
//
//    }
}
